Gestational diabetes mellitus: risks and management during and after pregnancy

Abstract

Gestational diabetes mellitus (GDM) carries a small but potentially important risk of adverse perinatal outcomes and a long-term risk of obesity and glucose intolerance in offspring. Mothers with GDM have an excess of hypertensive disorders during pregnancy and a high risk of developing diabetes mellitus thereafter. Diagnosing and treating GDM can reduce perinatal complications, but only a small fraction of pregnancies benefit. Nutritional management is the cornerstone of treatment; insulin, glyburide and metformin can be used to intensify treatment. Fetal measurements complement maternal glucose monitoring in the identification of pregnancies that require such intensification. Glucose testing shortly after delivery can stratify the short-term diabetes risk in mothers. Thereafter, annual glucose and HbA(1c) testing can detect deteriorating glycaemic control, a harbinger of future diabetes mellitus, usually type 2 diabetes mellitus. Interventions that mitigate obesity or its metabolic effects are most potent in preventing or delaying diabetes mellitus. Lifestyle modification is the primary approach; use of medications for diabetes prevention after GDM remains controversial. Family planning enables optimization of health in subsequent pregnancies. Breastfeeding may reduce obesity in children and is recommended. Families should be encouraged to help children adopt lifestyles that reduce the risk of obesity.

Figure 1

β-cell compensation for insulin resistance in GDM and control pregnancies. Data are from 99 Hispanic women who had GDM and 7 Hispanic women who maintained normal glucose tolerance during and after pregnancy. Both groups were studied with frequently-sampled intravenous glucose tolerance tests to measure acute insulin response and insulin sensitivity in the third trimester and then again remote from pregnancy. Curved lines represent insulin sensitivity-secretion relationships defined by the product of insulin sensitivity and acute insulin response in non-pregnant women for each group. Adapted from

Figure 2

Suggested management of women with prior gestational diabetes mellitus when risk appears to be for type 2 diabetes mellitus (T2DM). Assessment with oral glucose tolerance test and HBA_1C is recommended at 1–4 months postpartum to stratify risk. Women whose initial result is T2DM should begin treatment for that disease. Women whose initial result is impaired glycaemia are at high risk for T2DM. They should participate in intensive lifestyle modification^, to reduce weight and they should have HbA_1C levels checked every 3–6 months to assess response to treatment. Rising HbA_1C levels indicate an inadequate response. Women whose initial postpartum result is normal are at a lower, but still increased risk of diabetes mellitus. They should receive dietary and exercise advice to promote weight loss and be monitored at least annually by measurement of fasting plasma glucose and HbA_1C levels. Rising glycaemia, whether glucose or HbA_1C, is an indication of deterioration and a need for intensification of treatment. Adapted from reference.